Hanji's Experiment
by FangirlForReal
Summary: Levi and Eren's relationship is a secret only Hanji knows about. But Hanji might be a little too involved. When her experiments start to interfere with the secret relationship, things might get a little strange. M for strongly implied sexual relations and slight language. This is my very first story so please review and tell me what I can do better but please be gentle as well.


The chow hall at dinner was just as loud as ever. The 104th cadets were always the loudest. Eren and Jean were yelling at each other – again – while Eren's genius but weak blondie friend, Armin tried to get them to settle down. Meanwhile, Connie was loudly accusing Sasha of stealing his bread which she was currently stuffing her face with (at least that kept her quiet). The tall freckled girl with the ponytail was complaining to anyone that would listen that the pretty blonde of the group was paying too much attention to a certain trio and not enough attention to her.

Of course they wouldn't shut up till the pretty girl with the red scarf came in and distracted Jean, Berthold gave his bread to Connie, and Krista finally turned her attention to Ymir.

None of them noticed a certain black haired corporal sitting on the other side of the room with an annoyed expression looking their way. They might have quieted down sooner if they had. Levi had that effect on people. He quite liked that about himself.

Once the rowdy bunch got a bit quieter Levi could focus better on the "exciting" news Hanji had for him. Not that he cared. He was more interested in his cup of tea. Hanji's experiments were her life, and as such, they were all she ever talked about. And she never shut up. Ever. But he tried to be interested anyways. At least until he was done with his tea. Then he would promptly leave her to ramble to someone else while he actually got some work done. That was the plan until he heard a familiar voice calling his name.

"Um..Levi-heichou" _Why does he always sound so scared when he says my name? Oh, right. I almost beat the life out of him. Well, he doesn't_ always _sound scared._ Levi remembered the times Eren was quite happy saying his name but left the thoughts quickly before he got carried away.

"What is it, brat?" Levi looked up from his tea to find his favorite (he would never tell anyone so) burden looking like a kicked puppy standing behind him. Levi quite liked that look (he'd never tell anyone that either though Eren knew perfectly well what faces he liked).

"I have something I'd like to talk to you about," That was usually Eren's way of hinting at his desire for the older man. Levi did a quick run through in his mind of all the things he had to do before the next day just to make sure he had sufficient time for his favorite toy.

"Alright, be in my office in an hour." he said nonchalantly. The younger boy's eyes lit up just a little before he mumbled a word of gratitude and ran off to catch up with his friends.

Levi turned back to Hanji who had been listening to the short exchange. She gave Levi a mischievous grin and winked. She was the only one who knew about the relationship between the boy and the corporal. Levi stared blankly at the woman, recalling the evening she had so rudely burst into his quarters on one of the occasions that the man and the boy expressed their feelings for each other. She knew by the way he glared at her that night that if she said anything about it to anyone, titans would be the least of her worries.

Levi practically grunted at the eccentric woman, threatening her with his eyes, "What are you looking at, Shitty-glasses?"

She ignored his irritated tone as usual, "Oh nothing! But speaking of nothing, there's an experiment I'd like to try with Eren tomorrow. Might I steal him away from training? This particular experiment will probably make him tired and unable to continue training for the day."

Levi almost asked what the experiment was but caught himself before he was stuck listening to this crazed woman for hours on end. "Fine, but he better be able to function when you're done."

"Oh, he'll function just fine for you." Hanji grinned mischievously again.

Levi had a bad feeling about this experiment of hers but ignored it. Hanji was glad he didn't ask. Little did he know that this experiment had as much to do with Levi as it did with Eren.

Later that night, Levi walked into his office to find a tired looking Eren sitting in one of the chairs. He closed and locked the door, and without hesitation, walked up behind Eren, put his lips to Eren's ear and said seductively in his deep voice, "Are you ready?"

Eren gasped just a little and visibly shivered. Levi loved that. It was all the answer he needed. He had been waiting for this all day. He walked to the door that separated his office and his quarters, unlocked it, and walked in, waiting for Eren to follow which he did. Levi locked the door behind him, grabbed Eren by the front of his shirt, and pulled him down to his level so he could kiss him roughly. Eren loved the way Levi dominated him and Levi loved dominating. Levi pushed Eren onto the bed and dominated the rest of the night.

The next day, after lunch, Eren made his way to Hanji's lab. He was particularly nervous for this experiment. He had been told it would put him out of commission for the rest of the day, and he was already tired from not sleeping the night before. Memories from the previous night flashed before his mind's eye and he had to quickly change his focus to something more appropriate before he got carried away. Now was not the time to reminisce about his pleasurable nights with his favorite shorty. He wondered if they would ever be able to tell anyone about their relationship. They would have to eventually. Eren had no plans for ever being without the intimidating man. He knew Levi felt the same, though he rarely expressed such sentiments. And it wasn't just because of the sex. They trusted each other. They knew each other better than anyone else. They could laugh together, something that neither of them did with many other people. The connection they shared was something that neither of them wanted to lose. But how could they tell anyone? Their relationship wasn't exactly sanctioned.

Eren stopped outside Hanji's lab and knocked on the doorframe, "Hanji-san, are you- ah!" Eren jumped as Hanji suddenly appeared directly in front of him, scrutinizing him.

"Nope, surprise doesn't work" she said as she scribbled some notes into a book.

"Uh..Was that all? Can I go?"

Hanji looked up from her notes with an evil look in her eye, and a smile on her face. "No. I have much more interesting experiments for you today! Follow me titan-boy!" She walked further into the lab, setting her notebook on one of the counters. Eren followed her to his usual testing bed and laid down.

"What exactly are you going to do?" He asked nervously.

"We've recently created a new concoction." She picked up a needle and syringe, and a small vial of a pinkish liquid. "We already know it works so don't worry about that." She proceeded to fill the syringe with the pink liquid and ready it for injection. "I want to see how it affects your titan ability."

That was the shortest answer she had ever given to that question which made Eren worry even more. Nevertheless, he pulled up his shirt sleeve like usual and prepared himself for the pinch of the needle in his skin.

"Here we go!" said Hanji excitedly.

Eren closed his eyes and felt the familiar pinch in the crook of his arm. When it was over, he opened his eyes, and looked at Hanji's expectant face. After a few moments he said sheepishly, "I don't feel any different.."

"That's okay. It might take a while to have an effect."

Right at that moment, Eren started to feel very strange. It hit him like a ton of bricks. "Hanji, I don't feel…" and suddenly everything went black.

Hanji grinned triumphantly as she watched the changes slowly take place. _It worked!_

The next morning greeted Levi with harsh sunlight and a very excited Hanji.

"What the hell, Four-eyes?" Levi groaned angrily. He sat up and Hanji handed him a cup of tea which he took.

"My experiment with Eren went very well yesterday, and I'd like to show you the results!" Hanji seemed especially excited about this new experiment.

Levi took a sip from the tea, stretched out his hand, and said in an irritated voice, "Alright, give me the report."

Hanji shook her head and said, "These results you have to _see_." Something was definitely going on.

Levi stared at her, suspicious, but then got up and literally kicked her out of his room so he could shower and dress. "Fine, I'll be at the lab in ten minutes. This better be good, Shitty-glasses."

Hanji left Levi's quarters and practically ran back to her lab to make sure her subject hadn't woken up without her. The transformation had finally finished! She walked to the side of the bed where Eren lay and gently shook the figure on the bed awake.

Eren's eyelids fluttered open to the sight of a very excited Hanji. Realizing the time, the teenager suddenly started rambling, "I'm sorry, Hanji! I started to feel strange and passed out. Did your experiment not work?" He noticed his voice sounded slightly different, but attributed it to having slept for so long.

"Oh, it worked!" squealed the scientist.

That's when Eren noticed the strange feeling. Something felt wrong. The teenager sat up only to realize something important was missing and other things had been added. Hanji grinned as understanding dawned on Eren's beautiful features.

"Hanji! What the hell did you do?!" Levi stood a few feet away staring in shock (not a common emotion for the man) at his boyfriend turned girlfriend. He had to admit, Eren made a beautiful female. Hi-..Her face was more feminine somehow but he could still tell it was Eren. Her hair was chocolate brown, shiny and flowed down to her breasts which weren't exactly small but not particularly large either. Her waist was smaller and her hips wider. She looked just a little bit more petite and not as muscular. Those were all the changes he could see, but he knew there were more. Eren looked just as shocked although he was silent.

"Now Levi, I know you're probably upset-"

" _ **Upset?! I'll kill you, Shitty-glasses!**_ " Levi lost all the composure he usually had. He was about to lunge toward the scientist who had swiftly turned and started running, when his way was suddenly blocked by Eren.

"Wait, Levi. Think for a second. You're okay with girls too, right?" Eren was desperately trying to calm humanity's strongest down. Levi was glaring at the doorway where Hanji had escaped.

"Well, I guess, but I'm not okay with that crazy scientist screwing with my lover!" Levi was huffing away in pure anger. Eren had never seen him so riled up. He usually had a mask of superiority to put on when he was angry.

"Levi, I'm still Eren. Look!" Eren dared to make Levi look at her by taking his face in her hand and making him face her. Levi was met with the sight of his favorite green eyes. Eren smiled the same way she always had. Levi calmed down a bit more, and Eren could see it in his grey eyes. "It's okay."

"What the hell is wrong with you? How can you be so calm?" Levi questioned.

"How are you not? Where's your composure?" After a moment of silence, Levi's expression returned to one of irritation. He looked like he did when one of the cadets failed to clean properly. "I'm fine, I think. I've never been a girl before so I don't know how it's supposed to feel. I mean, it feels weird with certain additions," she gestured toward her chest, "and..uh..subtractions.." she didn't gesture this time. Then she had an idea of how she could get Levi to really calm down. "Hey Levi, I have something I'd like to talk to you about," she said with more confidence than usual. Levi didn't seem to notice her confidence or the meaning behind her words.

"Alright, let's go to my office." Levi said, obviously upset with the situation. Eren grabbed his hand and started running down the hall towards his office. "Calm your tits, and stop running, Shithead!" Levi yelled, annoyed. Instead of going to his office door, however, Eren went straight to the door leading to his quarters. She pulled him in and made sure both doors were locked. Levi sat down in the chair in front of his desk facing his boyfr-girlfriend. He still hadn't realized what Eren was planning. He put his elbows on his knees and rested his chin on his fists. Eren kneeled in front of him so they were eye to eye, and looked at him.

"Levi, I want to try something. I think it will make you feel better."

"I'm fine, brat." he lied. Eren leaned forward and pecked Levi's lips with his own.

Levi noticed then that female Eren's kisses felt and tasted just like male Eren's. Eren kissed him again with a little more force and for a little longer, testing the waters. When Levi put his hand on the back of her neck and kissed her back, Eren took that as the okay. She stopped holding back. She shifted so she was sitting on Levi's lap, straddling him. Her lips parted as she deepened the kiss. Levi's tongue found hers, and the kiss deepened even more. Levi's hands started exploring this new body. It was softer than he was used to but mostly the same otherwise. Thighs, butt, back, sides, all of it felt almost familiar. Breasts were new but that didn't mean he didn't like them. They both noted how at least the kiss felt the way it always had. They parted and Eren moved her lips to Levi's neck and down to his collarbone, panting. Even her hair smelled the same. In this position, it was obvious when Levi started growing hard.

Eren pulled away and asked, "Feeling better?" Levi looked at her with just a little conflict in his eyes, a look she had never seen him wear. "I'm still me. My gender is the only thing that's changed." Levi continued staring at her for a moment before he leaned forward and kissed her again.

When he pulled away he said, "Shithead, of course I know that." Eren relaxed a bit and decided something.

"Levi. I want to try something else." She looked at the man in front of her. "I've never thought of what it would feel like to have sex as a girl…" At that, Levi turned just a bit harder. Eren noticed as well.

Levi looked up and her, "That would be a stupid thing to think about."

Eren took hold of his cravat and leaned in so that their faces were only centimeters apart. "Why don't you show me?" She stood, and backed up, pulling Levi out of the chair. She walked backwards till her calves found the side of his bed then let go of him and laid down.

"Gladly" he said, hungrily eyeing the waiting figure in front of him. The bulge in his pants was clearly evident now. They made quick work of stripping each other, not having to worry about a bra (since Eren obviously hadn't been wearing one when he changed) for which they were both very grateful.

That afternoon was one of the best that they could remember. Levi had been careful at first, fearing that it would be different. He was very pleased to find that it was just as amazing as usual. He stopped being careful when he realized how familiar it all was. Eren was still the sexiest thing he'd ever seen. She made the same faces, moaned the same, begged the same (maybe even a bit more which didn't bother Levi in the slightest), and had the same look in her eyes. When he came to terms with the fact that this was still his Eren, he stopped holding back.

Eren noticed. Sex with Levi was always amazing. It was even more so as a female. Having all the right equipment made her soar with ecstasy. It was the best sex she had ever had. When it was over, she thought of how unfair is was that women could feel all that. When she brought it up to Levi, he told her she only thought so because of her limited experience.

Lying wrapped up in each other in Levi's bed after that glorious afternoon, something occurred to Eren. "Levi?"

"Hm?" He continued playing with her newly long hair.

"What if I'm stuck like this?" she questioned.

"I'm sure Hanji can change you back." He answered lazily.

"But…what if I want to stay like this? Would you be okay with that?" She braced herself for whatever reaction he might have. He went still at her questions.

"What the hell kind of question is that?" He sounded just a bit tense.

"I just thought..well, maybe..maybe it would be nice. I mean, if I'm like this, we wouldn't have to hide anymore. And, maybe..someday..we could..we could have a family. Our own family." The more she thought about it, the more she liked the idea. She could start a family with Levi. Humanity's strongest soldier and humanity's hope could be happy.

"We'll talk to Hanji about it later."

"Okay."

The two lovers stayed this way for another hour, talking occasionally, when they heard a knock at the door. Levi got up and put his pants on. "Don't just lay there. Cover yourself with the blanket" he instructed Eren. She obeyed.

Levi opened the door a crack to find a worried looking Hanji. "What do you want Four-eyes? I'm busy." Levi said impatiently.

"Have you finished screwing my test subject?" Hanji said sassily.

"Have you finished shitting yourself worrying that I'd really kill you?" He replied with just as much sass.

"Levi, stop overreacting. The effects aren't permanent." Levi was surprised to hear that and instantly hoped Eren hadn't heard it. "H-she should be back to normal by tomorrow. You've already taken up most of the time I was going to use for experiments, so can I please have hi-her back?" Hanji pleaded.

"Alright, fine. But I'm coming with you."

Hanji smiled. "That's fine! I'll be waiting outside." She walked away, happy to have gotten past the terrifying man.

Levi closed the door and looked behind him at Eren. She was watching him with a calm expression. "Guess I don't have a choice. That's okay. I couldn't possibly face my squad as a girl!" She recoiled at the thought and smiled. Levi noted that Eren seemed less filled with rage as a female. He attributed it to estrogen and the fact that no one had mentioned killing titans.

"Come on. Get dressed, brat. We have experiments to go through." Levi said, reverting back to his old self.

They managed to make it through the building without running into any of Eren's friends. They even managed to grab a bite of lunch on the way. The experiments went well. Eren could still use his titan ability and Hanji had a field day experimenting on a "female" titan. By the time the experiments were done, they had missed dinner and found themselves exhausted. Levi sent Eren off to bed knowing that everyone else was already asleep. If he turned back to normal before tomorrow morning, no one would be the wiser as to what had happened that day.

After Eren was gone, Levi had a question for Hanji. "Hey, Shitty-glasses." She looked up from her notebook. "You made that stuff that changed Eren right?"

"Why yes I did." She replied, looking proud. She started blabbering about how she and her team had discovered it when Levi cut her off.

"I didn't ask how you made it, dumbass. I want to know if you can make it last longer." He said impatiently.

The scientist thought for a moment. "You mean make it permanent?"

"Did I say permanent? No. I mean make it last a year or two."

Hanji wondered what he was thinking and why he was asking. "Levi, I don't know what that would do to him. I mean it's not exactly normal to switch genders back and forth. Why are you asking?"

"I just.." He paused. Hanji had never seen the stern and stoic shorty at a loss for words. "I wonder if we could have kids together. I don't want him to change permanently. I love him for him. But it would be nice to have our own kids, even in this shitty world." He had never been this open with anyone but Eren, and for the first time since she had known him, Hanji saw hope in Levi's eyes.

She smiled. "I'll work on it."


End file.
